EP2222260B1 - Acoustic device for linear perceived-sound attenuation - Google Patents

Abstract

The present invention relates to an acoustic device for linear perceived-sound attenuation, comprising a channel along which the sound propagates from an entry to an exit, characterized in that it comprises, combined so as to make the perceived sound undergo a linear attenuation, at its entry, means for attenuating and setting into resonance sound propagating through the latter as far as at least one filter opening as exit, onto means for accentuating the filtered sound, in particular its short-wave frequencies, the accentuation means consisting of a frustoconical portion of the channel having a cross-section that increases from the housing towards the exit.

Description

The present invention is in the auditory field, particularly in the context of hearing protection.

The subject of the invention is an acoustic attenuation device, of the noise filter type.

Such a device will find a particular application as a hearing aid made to measure but also in the context of noise barrier plug.

More specifically, the present invention aims at a linear attenuation of perceived sound, unlike plugs and filters that attenuate sound selectively only at one or more parts of the auditory spectrum. The invention is intended to restore, attenuated, the entire acoustic spectrum, including the high frequencies corresponding to the medium and treble.

The state of the art already knows hearing aid filters having a linear attenuation of the perceived sound. However, the existing filters do not allow linear attenuation over the entire frequency range of the acoustic spectrum. In particular, the audible frequencies above 8000 Hz are strongly attenuated after filtration, generating a sharp fall on this range of the spectrum beyond this terminal. In the worst case, it may be a clipping generating a total disappearance of frequencies beyond said terminal.

In addition, another disadvantage of existing filtration devices lies in the fact that they do not take into account the psycho-acoustic criteria of interpretation of sounds. Where acoustics study nature and properties of sound waves, psychoacoustics refers to how they are captured by the auditory system and how they are interpreted by the brain. From this study, we deduce that the perception of the characteristics of a sound does not have objective measurement values.

In particular, clipping high frequencies destroys even harmonics from 10 to 16 kHz, the latter contributing to a pleasant sound or a so-called "musical" sound.

The present invention, as claimed, aims to overcome the disadvantages of the state of the art by providing an acoustic device for linear attenuation of sound over a wide band of the spectrum. The invention is designed to control the attenuation level and maintain a linear response after filtration for better listening comfort.

In particular, the invention offers the possibility of attenuating a sound without loss of harmonics and high frequencies. The invention produces an attenuated filtered sound comparable to a "loudness" effect, namely a frequency correction which makes it possible subjectively to obtain a more powerful sound when listening at low volume.

To illustrate the difference between the existing devices and the device according to the invention, reference is made to FIG. A. The latter represents attenuation in decibels (dB) as a function of the acoustic spectrum, expressed in Hertz (Hz).

The lowest curve, referenced G, corresponds to the attenuation of a plug, for example foam. Curves D, E and F transcribe the nonlinear attenuation of known devices. There is a decrease similar to the attenuation of a plug. Even if the curve D, which corresponds to a plug made to measure by molding, goes up from 4000 Hz, one notes a total loss of the frequencies the more acute beyond 8000 Hz.

An example of such a nonlinear attenuation device is described in the document EP 0 112 594 , wherein a molded hearing aid receives a nonlinear filtration device. The latter comprises a channel carrying the sound from an input to an output, the first portion of said channel being removable so as to allow the insertion of a filter at the end of its second portion.

Due to the small diameter of the channel, a cavity may be provided to prevent clogging by dust or grease particles. However, this cavity can cause uncontrolled acoustic disturbances.

In addition, the small section of said channel considerably attenuates the acoustic spectrum in medium frequency and completely closes the high frequencies, beyond 8000kHz.

The document US 5113967 describes a device using a system of amplification, filtering and attenuation in a different order from that of the invention. The result is a similar effect, but limited to the frequency range 500 - 6000 Hz

Curve C corresponds to a linear filtration device previously mentioned. We note that the curve is increasing on average up to 4kHz and decreasing.

On the contrary, the curves A and B, representing the attenuation of two embodiments of filtration device according to the invention, are reversed, generating the acoustic effect called "loudness", pleasant to the ear since such curve respects the tonal balance of the human ear.

To do this, the present invention combines opposing technologies consisting of, on the one hand, linearly attenuate the perceived sound and, on the other hand, obtain a resonance of the latter. Moreover, the sound is amplified at the output of the device according to the invention, through a projection phenomenon in order to accentuate the shortwave frequencies, ie medium and high frequencies. Thus, the invention can linearly attenuate a perceived sound, without losing the sound and quality of the latter, by restoring the high frequencies, especially beyond 8kHz. This results in a more natural "loudness" attenuation effect in the ear, through a stronger attenuation in the lower sensitive frequencies and by raising the high frequencies, offering a linear perception.

In addition, a particular embodiment in the context of custom molded prosthesis can significantly improve the audio quality, obtaining a more natural and musical sound.

The invention as described in claim 1 therefore relates to an acoustic device for linear attenuation of perceived sound, comprising a channel conveying said sound from an input to an output, characterized in that it comprises, combined in order to confer a linear attenuation of the perceived sound, at the input, attenuation and resonance means of said sound conveying the latter to at least one filter opening, at the output, on means of accentuation filtered sound, in particular its shortwave frequencies, said enhancement means consisting of a portion of said frustoconical channel of increasing section from said housing to said outlet.

The invention as described in claim 7 also relates to a noise cap, comprising such an acoustic device.

The invention as described in claim 8 further relates to a hearing prosthesis, made by custom molding and shaped to receive and receiving said acoustic device

• la figure A est une représentation comparatives des courbes d'atténuation des dispositifs de l'état de la technique par rapport à l'invention.
• la figure 1 représente une vue en perspective d'un dispositif acoustique selon un mode de réalisation de l'invention ;
• la figure 2 représente une vue de coupe du dispositif de la figure 1 ;
• la figure 3 représente une vue en coupe du dispositif de la figure 1 selon un autre mode de réalisation.
• la figure 4 représente une vue en perspective d'un dispositif acoustique selon un autre mode de réalisation de l'invention ; et
• la figure 5 représente une vue de coupe du dispositif de la figure 4.

Other characteristics and advantages of the invention will emerge from the following detailed description of non-limiting embodiments of the invention, with reference to the appended figures in which:

• Figure A is a comparative representation of the attenuation curves of the devices of the state of the art with respect to the invention.
• the figure 1 represents a perspective view of an acoustic device according to one embodiment of the invention;
• the figure 2 represents a sectional view of the device of the figure 1 ;
• the figure 3 represents a sectional view of the device of the figure 1 according to another embodiment.
• the figure 4 represents a perspective view of an acoustic device according to another embodiment of the invention; and
• the figure 5 represents a sectional view of the device of the figure 4 .

The present invention relates to an acoustic device for linear attenuation of perceived sound.

In a preferential but nonlimiting manner, according to the embodiments shown in the drawings, such a device has a generally cylindrical shape.

It comprises a channel 1 formed inside said device, crossing the latter longitudinally. This channel 1 carries the sound from an input 2 to an output 3 located at each end of said channel 1, opposite to each other.

Throughout this channel, the invention provides means capable of attenuating, resonating, filtering and accentuating said sound, and whose combination allows an attenuated restitution. linearly of the entire acoustic spectrum, in particular attenuation of high frequencies, especially beyond 8kHz.

In other words, the device according to the invention allows the sound, namely that it takes the sound in its frequency content as it arrives at the input 2, maintaining this spectral content while attenuating and then equalizing it . The result, close to a "loudness" effect, is achieved by reducing the sound as the ear naturally does, while offsetting the extreme frequencies, namely by exciting the frequencies below 2kHz and above 8kHz.

To do this, at input 3, said device comprises means 4 for attenuating and resonating the sound. Preferably, these means 4 are constituted by a first portion of said channel 1 open on the outside at the inlet 3. The dimensions of this portion change the attenuation or resonance of the perceived sound. Therefore, the length of the means 4 is determined according to the desired resonance. Similarly, the section of the means 4 is determined according to the desired attenuation.

Preferably, but not exclusively, the means 4 make it possible to accentuate the highs before filtration.

This result can be obtained through a large section width and constant until filtration. In particular, this width must be related to its length to maintain a ratio allowing resonance and resonance of the waves until filtration.

As a non-limiting example, visible on the figure 3 , the first portion of the channel 1 constituting the means 4 may have a circular inner section with a diameter of 4 mm while it has a length of 4.5 mm between inlet 2 and filtration. To achieve a similar effect of frequency resonances, this embodiment provides a larger width relative to its shorter length.

Compared to another embodiment, visible on the figure 5 , this section can measure 1.4 mm while the length is 6.1 mm. As mentioned above, the section is smaller because of a longer length.

Be that as it may, the minimum section of channel 1 input 2 must be at least 0.5 mm in order to pick up a wave with the widest possible acoustic spectrum, especially without clipping high frequencies. Compared with the state of the art, this large inlet width 2 reduces the attenuation with respect to a smaller section, of the order of one-tenth of a millimeter, from 0.1 to 0.2 mm.

In general, the means 4 convey the sound to filtration means.

According to one embodiment, visible on the figure 2 these means 4 open into a housing 5 for receiving said filtering means in the form of at least one filter 6. This housing 5 is in the form of a cavity of suitable dimensions, on the one hand, to receiving said filter 6 and, secondly, to maintain the sound in resonance. In this case, the width of said housing 5 is equivalent to that of the filter 6 so as to maintain the latter within the cavity. The resonance here again depends on the length of said housing 5, before and / or after the filter 6, but also along the latter.

As such, said filter 6 is chosen according to the desired acoustic characteristics. More particularly, according to a nonlimiting embodiment, the filter 6 comprises standard dimensions. It can be of any type, more particularly impedance sound resistance type. Such a filter makes it possible to obtain a regulated curve, in the manner of an "acoustic damper".

This filter can be placed in front of the cavity, directly at the outlet of the means 4, in the center thereof or back. The positioning of the filter 6 is studied so as to modify the sound according to the envisaged result.

In sum, the housing 5 enclosing the filter 6 acts as a filter resonator. Note that the housing 5 enclosing the filter 6 can align with the first portion of the channel 1, forming the attenuation means 4, providing continuity in maintaining the frequency resonance.

According to another embodiment, visible on the figure 3 said filter 6 is placed at the end of the means 4, at the outlet of the latter, so that the sound opens directly onto said filter 6.

It can be seen here that the section of the channel 1 has been enlarged optimally to improve the sound resonance.

In addition, at the output 3 of said device, means 7 are provided for accentuating the filtered sound. These are arranged at the outlet of the housing 5 and receive as input the filtered sound.

These means 7 create a pavilion effect generating a projection phenomenon. In particular, they emphasize shortwave frequencies such as midrange and treble. These means 7 thus make it possible to re-energize the previously attenuated frequencies, contributing to the "loudness" effect and the musicality of the sound at the output 3.

To do this, said accenting means 7 consist of a portion of said frustoconical channel of section 1 increasing from said housing 5 to said outlet 3. The section and the taper angle of said accenting means 7 are determined according to the desired accentuation of the sound.

In addition, the taper angle may vary depending on the length. As mentioned above for the attenuation means 4, a longer length of the cone makes it possible to obtain at a lower angle ( figure 5 ) a comparable result with a larger angle for a shorter length ( figure 3 ).

In the case visible on the figure 3 the filter 6 is inserted directly into the input of said accenting means 7. In this case, in this case, said filter 6 can be deprived of its protective envelope 8 so that its maintenance is carried along the walls of the walls. means 7 of accentuation by the edges 9 of its membrane 10, by force support.

On the other hand, depending on the embodiments envisaged, Figures 2 or 3 , the device according to the invention can be made in one or two parts. Indeed, the insertion of the filter 6 in the housing 5 requires that the device consists of two elements cooperating by interlocking.

While the configuration of the figure 3 allows to insert directly said filter 6, by interlocking force, then maintained by the constraint of the walls of said accentuating means 7. It is then no longer necessary to have two elements cooperating with each other.

The present invention also relates to an anti-noise plug, comprising an acoustic device as previously mentioned. In particular, the entire plug may be constituted by said device. According to another embodiment, said device can be inserted, enclosed or surrounded by said plug.

Such a cap of standard dimensions fits any type of ear. In addition, it may consist of a shape memory material, expanded foam type or the like, so as to be partly constrained and then to return to its original shape, locking in the ear of the user and attenuating the unfiltered noise sounds by the device according to the invention.

The present invention also relates to a hearing aid, made by custom molding. Adapted to the size of the ear of a user, such a prosthesis prevents all its parasite because it perfectly matches the internal contours of said ear.

Such a prosthesis is shaped to receive an acoustic device according to the invention and receives such a device. The latter can be removable or directly wrapped by the prosthesis during the molding step.

More particularly, in an example not forming part of the invention, such a prosthesis may comprise at the output a tube of section and length determined according to the audio result to be obtained. This tube contributes to obtaining a more natural attenuated sound perception sound through a phenomenon of reflection of the medium and acute frequencies along said tube.

The present invention therefore consists of a hearing protector capable of providing a linear attenuation of filtered sound with superior listening qualities and a more natural sound, through a combination of attenuation and then amplification of sound filtered, resonant throughout the device.

The specific dimensioning, in particular through a larger width decreasing the attenuation effect, makes it possible to cover a larger acoustic spectrum width, going up to high frequencies, beyond 8kHz and even up to 16kHz.

The invention thus makes it possible to restore these high frequencies perceived and filtered, conferring a loudness effect on the sound at the output 3.

Of course, the invention is not limited to the examples illustrated and described above which may have variants and modifications without departing from the scope of the invention as claimed.

Claims (9)

1. Acoustic device for linear attenuation of the perceived sound, comprising a channel (1) conveying said sound from an entry (2) to an exit (3), wherein it comprises, combined so as to confer a linear attenuation of the perceived sound, at the entry (2), means (4) for attenuating and setting into resonance of said sound conveying the latter to at least one filter (6), said means (4) extending over a constant cross-section width to within a housing (5) designed for receiving said filter (6), the latter coming out, at the exit (3), onto means (7) for accentuating the filtered sound, in particular its short wave frequencies, said accentuation means consisting of a frustoconical portion of said channel (1) having a cross-section that increases from said housing (5) toward said exit (3).
2. Acoustic device according to claim 1, wherein said attenuation means (4) are formed of a portion of said channel (1) over a length determined according to the desired resonance desired.
3. Acoustic device according to any of the claims 1 or 2, wherein said attenuation means (4) are formed of a portion of said channel (1) according to a cross-section determined according to the desired attenuation.
4. Acoustic device according to any of the preceding claims, wherein said housing (5) is in the form of a cavity having appropriate dimensions, so as to, on the one hand, receive said filter (6) and, on the other hand, maintain the sound in resonance.
5. Acoustic device according to any of the preceding claims, wherein the length, the cross-section and the conicity angle of said accentuation means (7) are determined according to the desired accentuation.
6. Acoustic device according to any of the preceding claims, wherein the entry cross-section (2) has a diameter of at least 0.5 millimeters.
7. Earplug, comprising an acoustic device according to any of the preceding claims.
8. Hearing aid, made by molding to measure and formed so as to receive and receiving an acoustic device according to any of the claims 1 through 6.
9. Hearing aid according to claim 8, comprising, at the exit, a tube the cross-section and length of which are determined according to the audio result to be achieved.

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